Amazon’s Just Walk Out technology is both extremely cool — just grab what you want and walk out the door, no checking out or paying necessary — and extremely complicated. Amazon’s system uses computer vision, which requires a complex system of cameras and sensors just to make the whole thing work.

The system is pretty straightforward: each item, in this case mostly clothing, gets an RFID tag that looks like a normal clothing tag. Customers come into the store, pick out what they want, and walk through an “exit gate” that scans the tags and tallies up the bill. Then they scan their credit card or wave a palm over an Amazon One scanner and leave.

It may not feel quite as cool to go through a scanner before you leave as it does to just walk out of the building, but the pitch for Amazon here is that an RFID system will be drastically easier for companies to implement. Rather than wire their buildings with an expensive camera system, they can just switch their tags, add a few gates, and be done. Amazon says its Just Walk Out testing has shown huge increases in customer traffic thanks to the shorter lines and many more transactions because the process is so simple.

Amazon itself may be pulling back on physical retail stores, but it’s clearly still invested in real-world shopping logistics problems. (Amazon says there are more than 150 total stores with Just Walk Out tech enabled.) It’s a potentially big business and, maybe even more enticingly, a huge source of customer data. If Amazon can get a palm swipe from everybody in every store everywhere, the internet’s most relentlessly optimized online store could know just as much about how you shop offline.